Guishan Island

Guishan lies about ten kilometres off the Yilan coast and is visible from most of the plain, a humped volcanic island that from the shore reads unmistakably as a swimming turtle. It is still hydrothermally active. Off its eastern cliffs, undersea vents pump sulphurous fluid into the sea and turn a patch of water a pale opaque blue-white, which the boats circle so that people can see the colour boundary and smell the sulphur. Landings on the small settlement side are controlled by daily quota, with a separate and smaller quota for the long stair climb up the shell of the island. The waters between the island and the coast are one of the better places in Taiwan for watching dolphins.

What you actually see

• The milky sea - a pale sulphurous plume where undersea vents discharge beneath the eastern cliffs.
• The turtle profile - the island's shape from the water and from the Yilan coast road.
• Dolphin watching - spinner and bottlenose dolphins in the channel, often in large groups.
• The stair climb - a long flight up the island's high ground, on a separate and smaller quota.

When to go

The island is generally open from around March to November and closed over the winter, when the northeast monsoon makes the crossing untenable. Permits are quota-limited and summer weekends sell out well ahead, so book through an operator in advance. Morning departures have calmer seas and better light on the vent plume.

Honest expectations

Trips are cancelled often and at short notice for sea state, and refunds depend on the operator. The crossing is short but rough enough that seasickness is common. Landing and climbing quotas are separate, and many people book only the boat circuit and are surprised they cannot go ashore. The stairs are steep, exposed and hot, with no shade at the top.

Nearby

Wushi Harbour and the Yilan coast are the departure point, with Jiaoxi hot springs inland.